Tropical Cyclone Berguitta is intensifying in the southern Indian Ocean and is likely to have a major effect on the 'island paradises' of both Mauritius and Reunion.

There remains a great deal of uncertainty regarding the track of Berguitta. It is currently over open water, but forecasts suggest it will track very slowly towards the southwest, striking Mauritius around 00:00GMT on Thursday.

At 09:00 GMT on Monday, Berguitta was the equivalent of a Category 1 storm on the five-point Saffir-Simpson scale, with sustained winds of 140 kilometres per hour (km/h). Wave heights of more than seven metres were also observed.

As Berguitta continues to feed off the warm waters of Indian Ocean, it will intensify into the equivalent of a Category 3 system, with sustained winds of 185km/h.

By the time the cyclone strikes Mauritius, it may have weakened marginally, but the winds will still be strong enough to cause "extreme damage".

Mauritius can expect a direct hit from a cyclone roughly once every five years. The last Category 3 equivalent storm to hit the island was Cyclone Hollande in February 1994 which killed two people, destroyed 450 homes, and caused $135m in damage.

Although winds from these cyclones attract news headlines, it is often the storm surges, flooding and mudslides which result in the greatest loss of life.

Fortunately, Mauritius is the first small island developing state in the Indian Ocean to have its own tide and storm surge early warning system.

This may well prove necessary because the island has one of the highest population densities of any country on Earth, and cyclones in this region can produce vast amounts of rainfall.

The island of Reunion, 220km to the southwest, holds numerous rainfall records from systems similar to Berguitta.

For example, Cyclone Denise struck the island on January 7 to 8 of 1966. The site of Foc-Foc recorded 1,825mm in 24 hours - a record that still stands.

That was no fluke, either. The island holds two 48 hour rainfall records: 2,467mm in March 1952, and 3,000mm in February 1993.

Rainfall could again be the major weapon in Berguitta's arsenal, as it is moving at barely walking pace, allowing it to drop much more rain than a faster moving system.